Ultrashort wave tube



March 16; w A A H 2,074,253

' ULTRASHORT WAVE TUBE Filed Aug. 1, 19:54

In ventor:

-- WWWQW conductor 'Patented Mar. 16, 1937 PATENT OFFICE ULTRASHORT WAVE TUBE Walter Diillenba ch, Berlin-Charlottenburg, Germany, assignor to N. V.

achinerieen-en Apparaten Fabriekcn"Meaf, Utrecht, Netherlands Application August 1, 1934, Serial No. 738,000

' In Germany July 21, 1933 13 Claims.

This invention relates to the generation of ultra-short wave oscillations by means of electron tubes.

By the works of Kohl (see Ergebnisse der 7, exakten Naturwissenschaften", 1930, page 275 sqq.) I it has become known to employ for the generation, reception and amplification of ultrashort electric oscillations tubes in which a structure capable of oscillation is disposed. In the.

in experiments made by Kohl the problem was to excite a. grid spiral circuit formed by the grid itself and an external shortcircuit bow with respect to its natural wave sothat it would emit electric waves in the manner of a magnetic dipole. l5 The present invention develops this idea further. For accurately fixing thefrequency which in the known arrangement is determined in a somewhat complicated manner by.the grid bow and the grid spiral the invention provides a tubu- 20 lar Lecher system which contains the electrodes as parts,- the radiation emitted by this Lecher sys-' tem being used for the transmission of energy.

According to our present knowledge, concentric Lecher systems have no outer field, as the outer completely surrounds the inner one, and it can be proved that this is actually the. case with respect to an ordinary Lecher-system. However, if a Lecher system of this type is used in an ultra-short Wave tube, physically changed 30 conditions appear to prevail. The exact theory of action could not be developed hitherto, though I it is probable that the'electrons oscillating in the tube bring about also on the outside of the external conductor an oscillating charge and thus 35 cause currents which originate the emission of electric waves whose polarization corresponds to the linear expansion of the Lecher system. It may be inferred from this polarization that stray rays which could possibly come out'at the open ends of the Lecher system are out of the'question, as they would have a'polarization vertical to that of the linear expansion of the Lecher system, so that it can be assumed that actually oscillating 45 chargeson the outsides of the outer tube are concerned. I Arrangements areknown, in which inside a tube Lecher systems are used as oscillation determining structures, but radiation isefiected by 50 them by means of special emitters coupled to the Lecher system, the system itself being absolutely prevented from radiation especially by positioning the feeders for the heating energy at the ends .carrying high alternating potentials.

' According to the invention, the voltage feeders continuation H.

are connected to nodes ofthe Lecher system so that radiation of the, latter is rendered possible. 7 Further features of the invention will be explained with reference to the accompanying drawing, in which Figure 1 is a diagrammatic view of a concentric Lecher system arranged in a tube and having a length M4; and Figs. 2 and 3 arediagrams of Lecher systems in which the length of the system is made like M2.

In'Fig. 1, the Lecher system is formed by the 1 anode A and its continuation A, the'grid G with the continuatiomGf, and the filament H-with The system is short-circuited at the end by the capacity C, and the entire system oscillates then as a M4 oscillator. The wavelength is thus exclusively determined by the linear length of the Lecher system and can be accurately maintained. A further advantage is that the feeders are already within the tube in a potential node and therefore absolutely free from high frequency, unlike the usual ultra-short wave .tubes, in which the feeders had to be constructed as tuned Lecher systems.

A further embodiment of the invention is shown in Fig. 2, in which the Lecher system is con structed as a V2 emitter. The feeders lie again on potential nodes of the system, or practically in the center of the emitter. In the tube shown the'characteristic impedance is considerably reduced in the left half of the Lecher system, though it is also possible to attach on both ends of the system the grid and filament, possibly as shown in Fig. 3, whereby the oscillatory power can be increased.

Practical experiments have shown that the tube oscillates as an electric M2 dipole. To attain a sharp directional effect it is sumcient to arrange at a suitable distance behind the emitter M2 reflectors in parabolic arrangement or to use a metal reflector. 40

I claim 1. An ultra-short wave tube, comprising a. vacuum receptacle, a cathode in the vacuum receptacle,- a grid concentric about the cathode, a solid wall anode concentric about the grid, a hollow outer-conductor connected to the solid wall anode, a hollow inner conductor spaced away from theouter conductor and connected to the grid and a condenser entirely within said vacuum receptacle coupling the inner and outer con ductors, the space between the outer and inner conductor, grid, solid wall anode and said condenser forming a resonator, the outer conductor formingan antenna. p

2. An ultra-short wave 'tube, comprising away from the outer conductor and connected 6, said to the grid and a condenser entirely within said vacuum receptacle coupling the inner and outer conductors, the space between the inner and outer conductor, grid solid wall anode and said condenser forming a resonator, the outer conductor forming an antenna, leads for the grid and for the solid wall anode connected to the inner and outer conductors at potential nodes, and cathode leads extending into the hollow inner conductor in the vicinity of a potential node.

3. An ultra-short wave tube substantially according to claim 2, the short circuit condenser being connected to the opposite ends of the outer and inner conductors from that of the grid and anode.

4. An ultra-short wave tube according to claim 2, the short circuit condenser consisting of said inner and outer conductors with their lengths extended to points in a direction opposite from said grid and said anode.

5. An ultra-short wave tube according to claim 2, said condenser consisting of a flange connected to the inner conductor and a flange connectedto the outer conductor, parallel to said first flange and together forming said short cir cuit condenser perpendicular to the axis of the resonator.

6. An ultra-short wave tube, comprising a vacuum receptacle, a cathode in the vacuum receptacle, a grid concentric about the cathode, a solid wall anode concentric about the grid, a hollow outer conductor connected to the solid wall anode, a hollow inner conductor spaced away from the outer conductor and connected to the grid, the space between the inner and outer conductor, grid and solid wall anode forming a resonator, the outer conductor forming an antenna, leads for the grid and solid wall anode connected to the inner and outer conductors at potential nodes, and cathode leads extending into the hollow inner conductor in the vicinity of a potential node, a flange connected to the inner conductor and a flange connected to the outer conductor, parallel to said first flange and together forming a short circuit condenser perpendicular to the axis of the resonator, and a metal plate perpendicular to the axis of the resonator forming a second short circuit condenser with the flange connected to the inner conductor.

'7. An ultra-short wave tube as claimed in claim 6, said metal plate having an opening at its center, one of saidcathode leads extending through said opening and the second cathode lead connected galvanically with the metal plate.

8. An ultra-short wave tubeas claimed in claim metal plate having an opening at its center, a cathode lead extending through said opening and a second cathode lead connected galvanically with the metal plate, the said resonator and said antenna being of a length M4.

9. An ultra-short wave tube, comprising a vac,- uum receptacle, a cylindrical hollow outer conductor comprising an anode at one end, an inner conductor spaced away from the outer conductor and concentric thereto and each of said conductors having a section of high wave'resistance and a section of low wave resistance, said sections of high wave resistance being concentric and said sections of low wave resistance being concentric, the latter forming a short circuit 4 condenser entirely within .said receptacle, a. grid upon said inner conductor at the end of the high resistance section and concentric to the outer conductor, the high resistance sections and grid formingta resonator, a cathode within the grid and leads connected to the inner and outer conductors at a potential node, whereby the outer conductor forms a di-polar antenna.

10. An ultra-short wave tube, comprising a vacuum receptacle, a cylindrical hollow outer conductor, an inner conductor spaced away from the outer conductor and concentric thereto and each of said conductors having a section of high wave resistance and a section of low wave resistance, said sections of high wave resistance being concentric and said sections of low wave resistance being concentric, the latter forming a short circuit condenser entirely within said receptacle, a grid upon said inner conductor and an anode upon said outer conductor at the end of .the high resistance sections, the high resistance sections forming a resonator, a cathode within,

the grid and leads connected to the inner and outer conductors at a potential node in the vicinity of the transition point of the two sections, whereby the outer conductor forms a dipolar antenna, and leads connected to the cathode and traversing the inner and outer conductors at a potential node inthe vicinity of the transition point of the two sections.

11. An ultra-short wave tube as claimed in claim 10, the outer conductor and anode, the

inner conductor and grid and the di-polar antenna being of a length 7\/2, the short circuit condenser and the resonator being of a length M4.

12. An ultra-short wave tube comprising a vacuum receptacle, a cylindrical hollow outer conductor, an inner conductor concentric. thereto, solid wall electrodes at the ends of the outer conductor, grids at the ends of the inner conductor, cathodes concentric with the grids, the space between the. inner and outer conductors forming a condenser and a resonator entirely within the receptacle, leads connected at potential nodes to the inner and outer conductors, leads extending to the cathodes within the hollow inner conductor, and outer conductor through a potential node, the outer conductor forming a di-polar antenna.

13. An ultra-short wave' tube comprising a and passing through the center of the inner and outer conductors, the outer conductor forming a 'di-polar antenna of the length M2.

WALTER DKLLENBACH. 

